This invention relates to a disposable syringe of the prefilled type. More particularly, it relates to a prefilled, disposable syringe assembly wherein the medicament and diluent are contained in the syringe and separated by an intermediate slidable stopper. When it is desired to mix the components, a plunger stopper is moved toward the intermediate stopper with the intermediate stopper being moved adjacent a bypass channel formed in the syringe barrel. This permits intermixing of the components. Undesired compression of air in the syringe barrel is vented by means of a hydrophobic filter positioned in the nozzle portion. To administer the contents of the syringe, the filter is pierced by a piercing tubular member to which is attached a hypodermic needle.
There are currently available many types of disposable syringes wherein a medicament is sealed in the syringe barrel to be later combined with a diluent for the material with the syringe barrel having a bypass channel. Such syringe types are described in U.S. Pat. Nos. 2,896,622; 3,330,282; 3,477,431; 3,899,674 as well as Japanese Registration No. 1065744. There are also available wet/dry syringe systems wherein a filter is utilized in the syringe barrel to filter the contents prior to delivery. For example, in U.S. Pat. No. 3,757,779 an intermixing type syringe with a filter is disclosed. However, the prior art does not afford a wet/dry syringe system wherein intermixing of the wet and dry components can be effected in a single syringe barrel which is vented by means of a hydrophobic filter.
It is an advantage of the present invention to provide a novel preassembled mixing and hypodermic needle assembly which affords a venting of the syringe during the intermixing of the components. Other advantages are a syringe which is completely preassembled, a syringe which utilizes a hydrophobic filter as a vent means and a pointed tubular or cannula member for piercing through the filter for delivery of the mixed materials, and a syringe which affords intermixing of dry and wet materials in a single syringe barrel.